Отображение миниатюры в ВордПресс

// This theme uses a custom image size for featured images, displayed on "standard" posts.
add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 300, 9999 ); // Unlimited height, soft crop

<div id="primary" class="site-content">
<div id="content" role="main">
<?php if ( have_posts() ) : ?>

<?php /* Start the Loop */ ?>
<?php while ( have_posts() ) : the_post(); ?>
<?php get_template_part( 'content', get_post_format() ); ?>
<?php endwhile; ?>

<?php twentytwelve_content_nav( 'nav-below' ); ?>

<?php else : ?>

<article id="post-0" class="post no-results not-found">

<?php if ( current_user_can( 'edit_posts' ) ) :
// Show a different message to a logged-in user who can add posts.
?>
<header class="entry-header">
<h1 class="entry-title"><?php _e( 'No posts to display', 'twentytwelve' ); ?></h1>
</header>

<div class="entry-content">
<p><?php printf( __( 'Ready to publish your first post? <a href="%s">Get started here</a>.', 'twentytwelve' ), admin_url( 'post-new.php' ) ); ?></p>
</div><!-- .entry-content -->

<?php else :
// Show the default message to everyone else.
?>
<header class="entry-header">
<h1 class="entry-title"><?php _e( 'Nothing Found', 'twentytwelve' ); ?></h1>
</header>

<div class="entry-content">
<p><?php _e( 'Apologies, but no results were found. Perhaps searching will help find a related post.', 'twentytwelve' ); ?></p>
<?php get_search_form(); ?>
</div><!-- .entry-content -->
<?php endif; // end current_user_can() check ?>

</article><!-- #post-0 -->

<?php endif; // end have_posts() check ?>

</div><!-- #content -->
</div><!-- #primary -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>